Number Of Equal Channel Angular Extrusion Passes Research Articles

Effect of Severe Plastic Deformation on Wear Resistance of Sintered Al–Sn Alloys under Dry Friction Against Steel

The effect of equal channel angular extrusion (ECAE) with route A on the wear resistance of sintered Al–Sn alloys has been studied in this work. The tribological tests were carried out according to the “pin-on-disk” scheme without liquid lubrication. It was established that multiple processing by this method leads to the strengthening of the aluminum matrix and the formation of a structure with alternating Al and Sn layers which is favorable for the self-lubrication process. The wear resistance of the sintered Al–Sn alloys is increased as a result. However, the number of ECAE passes should be limited to two to three because a fragmentation of thin tin interlayers and destruction of the layered structure take place after large number of the passes.

Enhancement of Tensile Ductility of Severe Plastically Deformed Two-Phase Zn-12Al Alloy by Equal Channel Angular Extrusion

Tensile properties (mainly the ductility and fracture mode) of two-phase Zn-12Al alloy subjected to severe plastic deformation (SPD) via multi-pass equal-channel angular extrusion (ECAE) following route-Bc were investigated. As a result of ECAE processing, elongation to failure (as a ductility) of the alloy increased substantially and continuously with increasing the number of ECAE passes. However, the majority of the tensile strains are obtained in the state of plastic instability and therefore the uniform strains achieved along the gage length are very limited for this alloy. On the other hand, the strength of the alloy increased with increasing the number of passes up to 2, above which it decreased. The alloy sample after four ECAE passes exhibited 168% total elongation to failure at room temperature, which was 26 times higher than that of the as-cast one. This result indicates that multi-pass ECAE is effective on improving the tensile ductility of binary Zn-Al alloys. The fracture mode of the as-cast alloy samples completely changed after multi-pass ECAE and the brittle fracture behavior of the as-cast alloy was transformed into the ductile mode after processing.

Flow stress anisotropy and Bauschinger effect in ultrafine grained copper

The effect of strain path and magnitude on the flow stress anisotropy and Bauschinger effect (BE) in ultrafine grained (UFG) copper was investigated. The material billets were deformed via multipass equal channel angular extrusion (ECAE) following several deformation routes. The monotonic stress–strain responses under tension and compression and forward compression/reverse tension response along three perpendicular directions were determined in each billet. It was observed that, in certain cases, the strong tension/compression asymmetry was in favor of tension as opposed to what has so far been reported for UFG materials, and an increase in the number of ECAE passes caused a decrease in yield strength along certain sample directions. Finally, the BE was found to be more pronounced for the lower number of passes. It was shown that crystallographic texture and grain size differences cannot be the only factors responsible for these unexpected observations. Grain morphology and grain boundary character are argued to be additional parameters that have to be taken into account. How these factors affect tension/compression asymmetry, flow anisotropy and BE in UFG copper and how they can help elucidating the observations are discussed.

On the fatigue behavior of ultrafine-grained interstitial-free steel

Abstract The present paper reports on the cyclic stress–strain response of body-centered cubic ultrafine-grained (UFG) interstitial-free (IF) steel severely plastically deformed at room temperature utilizing equal channel angular extrusion (ECAE). Low-cycle fatigue tests were conducted with various strain amplitudes and strain rates on samples obtained through different ECAE routes and number of ECAE passes in order to determine the optimum processing route(s) for improved fatigue response of this material. UFG IF steel is superior to its coarse grained counterpart under both monotonic and cyclic loading in terms of properties, such as stress ranges tolerated, strength levels attained, and the corresponding fatigue behavior. All UFG steels subjected to more than 4 ECAE passes exhibit stable cyclic stress–strain response. Moreover, it was shown that dynamic grain coarsening, which usually leads to cyclic softening in UFG materials, is not prevalent in the ECAE processed UFG IF steel. For representing the fatigue life of UFG IF steel, the parameter after Smith, Watson and Topper, which is an indication of energy dissipation per cycle, proved adequate while comparing materials obtained through different ECAE routes.

FORMING OF NANOSTRUCTURED MATERIALS — NUMERICAL ANALYSIS IN EQUAL CHANNEL ANGULAR EXTRUSION (ECAE) OF MAGNESIUM, ALUMINIUM AND TITANIUM ALLOYS

International Journal of Computational Engineering ScienceVol. 05, No. 02, pp. 417-424 (2004) No AccessFORMING OF NANOSTRUCTURED MATERIALS — NUMERICAL ANALYSIS IN EQUAL CHANNEL ANGULAR EXTRUSION (ECAE) OF MAGNESIUM, ALUMINIUM AND TITANIUM ALLOYSB. H. HU and J. V. KREIJB. H. HUSingapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore Search for more papers by this author and J. V. KREIJC/o Singapore Institute of Manufacturing Technology (SIMTech), 71 Nanyang Drive, Singapore 638075, Singapore Search for more papers by this author https://doi.org/10.1142/S1465876304002472Cited by:1 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractEqual channel angular extrusion (ECAE) is a promising technique for producing ultra-fine grained (UFG) or nanostructured materials based on the principle of simple shearing. Through analysis, it is shown that only the geometrical factor Φ, namely, the half-angle of the two intersecting channels, and the number of ECAE passes, N, affect the effective strain. The equivalent linear reduction ratio, r0/r1, is derived to describe the size reduction effect of an object such as a grain. The most effective intersecting angle (2Φ) is 90°. Compared to traditional area reduction extrusion, the deformation effect is equivalent to an area reduction ratio of 1 million or a linear reduction ratio of 1022 after 12 passes of ECAE. Magnesium AZ31B, aluminium 6061 and commercially-pure Titanium were used for the study. Three types of die designs for ECAE of each alloy were proposed and numerically analysed. The effective strain, von Mises stress, equivalent area reduction ratio and equivalent linear reduction ratio were compared for the three types of die designs based on the simulation results using ANSYS/LS-DYNA. The parameter Nμ→nm, namely, the number of passes of ECAE required to reduce 100μ structures into 100nm structures, was calculated for each design. A grain size of 100μ can be deformed into a nanostructure through as few as 12-17 passes of ECAE.Keywords:Equal channel angular extrusion (ECAE)numerical simulationnanostructuresimple shearmaterials processingplastic deformation References M. C. Roco, J. of Nanoparticle Research 3(5-6), 353 (2001). Crossref, Google Scholar Kimet al., Scripta Materialia 45, 575 (2001). Crossref, Google ScholarL. R. Corwellet al., Materials Characterisation 37, 295 (1996). Google Scholar H. G. Selam, Proceedings of ICCE/9 (San Diego, July 1-6, 2002), p. 689 . Google ScholarV. M. Segal, Materials. Science. & Engineering. A197, 157 (1995). Google Scholar S. C. Chen, Z. Q. Wu, B. H. Hu, J. Liang & B. J. Wu, Hot-working Technology (Tsinghua University, 1992), p. 150 . Google Scholar FiguresReferencesRelatedDetailsCited By 1Finite element modelling and simulation of bulk material formingJaroslav Mackerle1 Apr 2006 | Engineering Computations, Vol. 23, No. 3 Recommended Vol. 05, No. 02 Metrics History KeywordsEqual channel angular extrusion (ECAE)numerical simulationnanostructuresimple shearmaterials processingplastic deformationPDF download